Summer

Summer proves his loyalty to Bran when the direwolf stands guard at his bedside for weeks following his "fall" from the tower at the end of "Winter is Coming." When an assassin enters Bran's bedchamber to finish the deed, Summer defends both Bran and his mother by tearing out the assassin's throat.

In the first episode of Season 2, "The North Remembers," Bran has a dream in which he sees the Godswood of Winterfell through Summer's eyes. As of the end of that episode, it is unclear if this was merely a dream, or if it implies some deeper connection between Bran and Summer.